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Re: CO2, backwater & vermiculite.

On CO2 & black water..
Paul Sears wrote:
> > One follow up question.  Claus Christensen mentioned to Karen Randall that
> > humic acids in the water column might goof up the chart.  I take it that
> > use of peat or various "black water" concoctions (or bog wood for that
> > matter) would put humic acids in the water column.  Do you or any of the
> > chemists have any comment on the use of the chart in that case?
>         If you have humic acids in the water, you are not likely to be
> able to get much idea of the HCO3- concentration (KH).  The charts
> are still all right, but that doesn't help much if you can't measure
> the KH.  You won't be able to _measure_ the CO2 very well, either.
As usual, I can only agree with Pauls comments. 'Semi' black-water tanks
are my pet interest, so I'd like to expand on this a little. Hopefully
without generating too much misunderstanding :).
The humic acids thoroughly foul up the easy 'direct' CO2 estimation
methods, at least those I'm familiar with. Worse, they'll invalidate a
few assumptions used to calculate the chart by providing an alternate
buffer system. Both the calculations based on the bicarbonate pKa and
methods used to determine KH won't be accurate any longer. 
From a hobbyists point of view, the combined effects on use of the chart
don't (IME) to amount to much. The chart will definitely provide a
better qualitative feel for whats happening in a 'black-water' tank than
the 'direct' CO2 kits.
I use soft water (~1.5 dKH) and add peat extract (made using an old
coffee percolator) 'till the water looks like weak tea. With CO2
injection the system buffers nicely at around pH 6.1. Your mileage may
vary, depending largely on the source of peat. The result is a
compromise between the demands of the fish and the plants. I've been
lucky with this compromise, recently cardinal tetras spawned in my
community tank and plant growth is mostly very rapid. One real advantage
is that the peat extract severly inhibits algae. The biggest downside is
that bio-filters won't work as well so good plant growth is more

on vermiculite avaliability..
Steve Pushak wrote:
>      Is vermiculite available in Europe?
>      I remember KB Koh had trouble finding vermiculite in Malaysia. KB, did
>      you ever come across it there?
>      How about other parts of the world like Australia?

You'll find vermiculite in many grades, hardly ever with the name
vermiculite :).
'Kitty Litter' is one source, but watch out for additives used to
prevent urine smells. A better (maybe even cheaper) source is 'Oil-Dri'
etc. It's used to mop up liquid spills in many industries, you might be
able to get some from a local garage.